See Section 26.15.12 for checking for perpendicularity in 2D geometry.
The is_perpendicular command determines if two objects are perpendicular.
Note that two lines must be coplanar to be perpendicular.
| is_perpendicular(line([2,3,-2],[-1,-1,-1]),line([1,0,0],[1,2,8])) | 
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| P1,P2:=plane([0,0,0],[1,2,-3],[1,1,-2]),plane([-1,-1,-1],1,2,-3],[0,0,0]); is_perpendicular(P1,P2) | 
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| L:=plane([2,3,-2],[-1,-1,-1]); is_perpendicular(L,P1) | 
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